Process of preparing manganese peroxid.



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To all whom it may concern:

Be'it known that I, Monouon L. Kemn, a citizen of the United States, and a resident of Brooklyn, in the county of Kings and State of new and useful Improvements in Processes of Preparing'Manganese lPeroxid, of which the following is a specification.

Manganese dioxid, on account of its oxidizing properties is a widely usedsubstance,

' and its most common use is for de olarizing 1 .purposes in the Le Clanch cell. t is found in nature in the form of a mineral, pynolusite. For its artificial preparation two reactions are known: (1). The decomp ition of manganese-nitrate at about- 17 0. centigmde-according to the equation:

generated from N0, by combining the latwith the g n of the air water:

2+ +H,O=2o,,

has found very little application, and the main reason for this is the low melting point of the nitrate, which causes the product to appear in the shape of a hardfsohd mass,

which mass, even after'pulverization, 'wasfound "inferior to the powdered mineral.

, In order to make this reaction available for and 1,1

the urpose of making a battery it W s roposed in U. S. Patents 1,160,999

l0,819 to mix with the nitrate the conducting material, such as carbon or graphite used in conjunction with the depolarizer in making up battery electrodes,

before decomposin the nitrate and changing it to dioxid. his way of working, on account of increasing the active surface to a .higher degree than it is possiblethrough mere mechanical pulverization has yielded excellent battery electrodes w e working on a laboratory scale but could not thus far be used on a larger scale. The reason for the difliculties encountered in applying this process in the manufacture of dry cells is the comparatively small quantity of solids Specification of Letters Patent.

ew York, have invented. certain electrode,

which the necessary proportion of depolarizer to conductin h 7 material permits to introduce in the liquld nitrate; the mixture Patented rat. a, rare. Application filed May 11, 1917. Serial Ito. 167,878.

remaining therefore in a liquid state and in order to insure an even distribution of --oonductlng material all through the mixture, the same has to be stirred during decompos1t1on. This stirring operation during the evolutlon of N0 a gas attacking nearly all metals, is the main obstacle to the use of the above process since it necessitates the use of special apparatusconstructed from special materials;

As to the second reaction, the oxidation of manganese carbonate by the oxygen of the air, though it has been found suitable for manufacturing on a large scale, still has the disadvantage that it cannot conveniently be carried to completion. This is due to the high resistance presented bythe pores of the partlcles' of the carbonate to the mm etration by gases, and for this reason, the

products of the air oxidation contain always a few per cent. of GO, combined with MnO. This last'mentioned impurity is in many cases hlghly undesirable, especially so. when the product is to \be used. for depolarizing purposes, since the presence of carbonate impairs the shelf life of the cell. As the removal of the carbonate by treatment with acid solutions was found impracticable for many reasons, chief amongwhich are, a decreased yield in manganese product and the tenacity with which acids are retained by manganese dioxid, itwasproposed in U. S. Patent 1,078,788 to oxidize these small quantities of carbonate by an aqueous solution of an oxidizing agent'such as mt l This'method, yielding as i does 2 highly eiiicient depolarlzer, still leaves room for further improvement, since the treatment with an expensive chemical such as 0,

adds to the cost of the product, secondly it introduces a few per cent. of manganese dioxid of a different origin, viz, from the reduction of O, and as this reduction,

as a general experience, yields a highly by drated manganese, the resulting products of 1 the permanganate treatment are therefore not entirely free from hydrates which might cause local action in a mall where such products have been introduced for depolarizing purposes;-but the main and most weighty objection to the above-mentionedprocess is,

for resince it does not include any st moving impurities, it is capable of giving good results only when working up a carbonate of a high degree of purity which property is seldom possessed by the commercial article. I

I have invented a new method of preparing artificial manganese of a high degree of purity and at an exceedingly small cost, which method consists in combinin the two reactions mentioned above in the ollowing manner:

.. Manganese carbonate heated above 300 .centigrade is exposed to the action of hot air for a period of a few hours, which treatment yields usually a product containing more than 70% MnO,. This product after coolin is moistened with from 10 to 20% nitric acld, figured on weight of product to be treated and according to contents of M110 and, in order to insure equal distribution of and penetration by the acid water is added in suflicient quantity to malre the mass appear dam all the way through. ThlS damp powder p aced in an acid resisting'retort or chamber with facilities for heating, is heated to drive off water and the excess of acid and the temperature is then gradually raised to decompose the manganese nitrate formed previously. As the decomposition point of nearly all nitrates lies much hi her than .that of manganese nitrate, all acid-solubleimpurities contained originally in the carbonate are now present in the form of sol-' uble nitrates which are easily removed by extraction with water. The resulting product after filtering and drying at low temperatures consists of a fine, dense, gray-colored powder resembling in appearance most closely the powdered mineral but is far superior to the latter in purity and eificlency especially as a depolarizer. Instead of treating the carbonate with air alone, It can be treated with air in the presence of a catalytic agent such as an oxid of nitrogen, in which case the period of the air treatment is considerably shortened and the temperature may be kept lower.

My invention is equally applicable for the treatment of manganese peroxid whether the same be artificial or mineral, for the removal therefrom of basic constituents or im urities. v

%hat I claim as my invention and desire to secure by Letters Patent, is:

1. A method of preparing artificial manganese peroxid, which com rises the heating of manganese carbonate ve 300 centigrade, exposing the same to hot air to yield a product containing MnO then moistening this product with a liquid containing nitric acid, heating the resultant damp powder to drive off moisture and excess of acid, then increasing the temperature to decompose the manganese nitrate previously formed, extractmg the residualnitrates with water,

. moisture and excess, 0

the resultant product being a fine dense powder. 2. A method of preparing artificial manganese peroxid, which comprises the heating of manganese carbonate above 300 centigrade, exposing the same to hot air to yield a product containing MnO moistenin this product with nitric acid with the ad 'tion of water in suflicient quantity to insure proper distribution of the acid and the dampening of the mass throughout, heatin the resultant damp owder to drive 0 f acid, then increasing the temperature to decompose the manganese nitrate previously formed, extracting the residual nitrates with water, and then filtering and d ing the material, the resultant produ'ct being a fine dense powder. 3. A method of preparing artificial manganese peroxid, whlch comprises the heating of manganese carbonate, exposi the same to hot a1r in the presence of a cata ytic agent to yield a product containi MnO moistenmg this product with a liquid containing nitric acid, heating the resultant damp powder to drive ofi moisture and excess of acid, then increasing the temperature to decompose the manganese nitrate reviously formed, extractin the residual nitrates with water, and t en filtering and the material, the resultant product being a fine dense powder.

4. A method of reparing artificial manganese peroxid, which comprises the .cess of acid, then increasing the temperature nese nitrate prev1- to decompose the ma ously formed, extractmg the residual nitrates with water, and then filtering and drying the material, the resultant product being a the dense powder.

5. A method of preparing artificial man-.4

ganese peroxid, WhlCh comprises the h of manganese carbonate, treating the same to yield a product containing applying nitric acid thereto, heating the re sultant powder to dry the same and drive off excess of acid and decompose the, manganese nitrate then present.

6. A method of preparing artificial manganese peroxid, which comprises the heat' of manganese carbonate above 300 centlgrade, exposing the same to hot air to yield a product containing MnO,, moistenin this product with nitric acid with the ad 'tion of water in suflicient quantity to insure proper distribution of the acid and the dampening of the mass throughout, heating the resultmg powder to dry the same and MnO,, then' III drive off excess of acid and decompose the manganese nitrate then present.

7. A method of preparing artificial mangan'ese peroxid, which comprises the heating of manganese carbonate, exposing the same to hot air in the presence of a catalytic agent to yield a product containing MnO moistening this product with a liquid containing nitric acid, heating the resulting powder to dry the same and drive ofi excess of acid and decompose the manganese nitrate then present.

8. A method of preparing artificial manganese peroxid, which comprises the heating of manganese carbonate, exposing the same to hot air in the presence of an oxid of nitrogen to yield a product containing M110 moistening this product with a liquid con-' taining nitric acid, heating the resulting powder to dry the same and drive of excess .bind such impurities and constituents to the acid, heating the resulting damp powder to dry the same and decompose the manganese nitrate formed, and removing the residual nitrates.

Signed at New York city, in the county of New York and State of New York, this 10th day of May, A. D. 1917.

MORDUOH L. KAPLAN.

Witnesses:

ARTHUR MARION, CHAS. C. GILL. 

